Effect of torrefaction on fuel properties of biopellets.

The study aimed to determine the effects of torrefaction on the fuel properties of pellets. Therefore, firstly, torrefaction parameters of rose (Rosa Damascena Mill.) oil distillation solid waste and red pine sawdust were determined through the torrefaction optimization process in terms of temperature and holding time. Then, using the selected torrefaction parameters, 14 different raw and torrefied pellets containing RP, PS, and Turkish Elbistan Lignite were prepared in different weight ratios. Finally, the fuel properties of the prepared raw and torrefied pellets, namely dimensions, proximate analyses, higher heating values, tensile strength, durability, abrasive resistance, and water uptake resistances, were investigated. The findings demonstrated that the higher heating values and carbon content of raw biomass samples increased while their volatile matter content decreased. The use of lignite at high concentrations led to an increase in ash content and a decrease in the strength and durability of pellets, which should be emphasized. In addition, red pine sawdust was used in place of solid waste from rose oil distillation solid waste to produce pellets with greater strength. All pellet mixtures with torrefaction had higher heating values and energy densities despite the fact that their mass and energy efficiency had decreased. It was determined that torrefaction increased the pellets' resistance to absorbing water and gave them a more hydrophobic structure. Thus, it was determined that torrefaction could enhance the crucial fuel parameters of the biomass samples.

Geometry and length control of 3D engineered heart tissues using direct laser writing.

Geometry and mechanical characteristics of the environment surrounding the Engineered Heart Tissues (EHT) affect their structure and function. Here, we employed a 3D tissue culture platform fabricated using two-photon direct laser writing with a high degree of accuracy to control parameters that are relevant to EHT maturation. Using this platform, we first explore the effects of geometry based on two distinct shapes: a rectangular seeding well with two attachment sites, and a stadium-like seeding well with six attachment sites that are placed symmetrically along hemicylindrical membranes. The former geometry promotes uniaxial contraction of the tissues; the latter additionally induces diagonal fiber alignment. We systematically increase the length of the seeding wells for both configurations and observe a positive correlation between fiber alignment at the center of the EHTs and tissue length. With increasing length, an undesirable thinning and "necking" also emerge, leading to the failure of longer tissues over time. In the second step, we optimize the stiffness of the seeding wells and modify some of the attachment sites of the platform and the seeding parameters to achieve tissue stability for each length and geometry. Furthermore, we use the platform for electrical pacing and calcium imaging to evaluate the functional dynamics of EHTs as a function of frequency.

Measurement of the low-frequency charge noise of bacteria.

Bacteria meticulously regulate their intracellular ion concentrations and create ionic concentration gradients across the bacterial membrane. These ionic concentration gradients provide free energy for many cellular processes and are maintained by transmembrane transport. Given the physical dimensions of a bacterium and the stochasticity in transmembrane transport, intracellular ion concentrations and hence the charge state of a bacterium are bound to fluctuate. Here we investigate the charge noise of hundreds of nonmotile bacteria by combining electrical measurement techniques from condensed matter physics with microfluidics. In our experiments, bacteria in a microchannel generate charge density fluctuations in the embedding electrolyte due to random influx and efflux of ions. Detected as electrical resistance noise, these charge density fluctuations display a power spectral density proportional to 1/f^{2} for frequencies 0.05Hz≤f≤1Hz. Fits to a simple noise model suggest that the steady-state charge of a bacterium fluctuates by ±1.30×10^{6}e(e≈1.60×10^{-19}C), indicating that bacterial ion homeostasis is highly dynamic and dominated by strong charge noise. The rms charge noise can then be used to estimate the fluctuations in the membrane potential; however, the estimates are unreliable due to our limited understanding of the intracellular concentration gradients.

Engineering a living cardiac pump on a chip using high-precision fabrication.

Biomimetic on-chip tissue models serve as a powerful tool for studying human physiology and developing therapeutics; however, their modeling power is hindered by our inability to develop highly ordered functional structures in small length scales. Here, we demonstrate how high-precision fabrication can enable scaled-down modeling of organ-level cardiac mechanical function. We use two-photon direct laser writing (TPDLW) to fabricate a nanoscale-resolution metamaterial scaffold with fine-tuned mechanical properties to support the formation and cyclic contraction of a miniaturized, induced pluripotent stem cell-derived ventricular chamber. Furthermore, we fabricate microfluidic valves with extreme sensitivity to rectify the flow generated by the ventricular chamber. The integrated microfluidic system recapitulates the ventricular fluidic function and exhibits a complete pressure-volume loop with isovolumetric phases. Together, our results demonstrate a previously unexplored application of high-precision fabrication that can be generalized to expand the accessible spectrum of organ-on-a-chip models toward structurally and biomechanically sophisticated tissue systems.

Frequency-Dependent Piezoresistive Effect in Top-down Fabricated Gold Nanoresistors.

Piezoresistive strain gauges allow for electronic readout of mechanical deformations with high fidelity. As piezoresistive strain gauges are aggressively being scaled down for applications in nanotechnology, it has become critical to investigate their physical attributes at different limits. Here, we describe an experimental approach for studying the piezoresistive gauge factor of a gold thin-film nanoresistor as a function of frequency. The nanoresistor is fabricated lithographically near the anchor of a nanomechanical doubly clamped beam resonator. As the resonator is driven to resonance in one of its normal modes, the nanoresistor is exposed to frequency-dependent strains of ε ≲ 10-5 in the 4-36 MHz range. We calibrate the strain using optical interferometry and measure the resistance changes using a radio frequency mix-down technique. The piezoresistive gauge factor γ of our lithographic gold nanoresistors is γ ≈ 3.6 at 4 MHz, in agreement with comparable macroscopic thin metal film resistors in previous works. However, our γ values increase monotonically with frequency and reach γ ≈ 15 at 36 MHz. We discuss possible physics that may give rise to this unexpected frequency dependence.

Direct laser writing for cardiac tissue engineering: a microfluidic heart on a chip with integrated transducers.

We have developed a microfluidic platform for engineering cardiac microtissues in highly-controlled microenvironments. The platform is fabricated using direct laser writing (DLW) lithography and soft lithography, and contains four separate devices. Each individual device houses a cardiac microtissue and is equipped with an integrated strain actuator and a force sensor. Application of external pressure waves to the platform results in controllable time-dependent forces on the microtissues. Conversely, oscillatory forces generated by the microtissues are transduced into measurable electrical outputs. We demonstrate the capabilities of this platform by studying the response of cardiac microtissues derived from human induced pluripotent stem cells (hiPSC) under prescribed mechanical loading and pacing. This platform will be used for fundamental studies and drug screening on cardiac microtissues.

Nanomechanical Measurement of the Brownian Force Noise in a Viscous Liquid.

We study the frequency spectrum of the thermal force giving rise to Brownian motion of a nanomechanical beam resonator in a viscous liquid. In the first set of experiments, we measure the power spectral density (PSD) of the position fluctuations of the resonator around its fundamental mode at its center. Then, we measure the frequency-dependent linear response of the resonator, again at its center, by driving it with a harmonic force that couples well to the fundamental mode. These two measurements allow us to determine the PSD of the Brownian force noise acting on the structure in its fundamental mode. The PSD of the force noise from multiple resonators spanning a broad frequency range displays a "colored spectrum" and follows the dissipation of a blade oscillating in a viscous liquid-by virtue of the fluctuation-dissipation theorem of statistical mechanics.

Matrix Pore Size Governs Escape of Human Breast Cancer Cells from a Microtumor to an Empty Cavity.

How the extracellular matrix (ECM) affects the progression of a localized tumor to invasion of the ECM and eventually to vascular dissemination remains unclear. Although many studies have examined the role of the ECM in early stages of tumor progression, few have considered the subsequent stages that culminate in intravasation. In the current study, we have developed a three-dimensional (3D) microfluidic culture system that captures the entire process of invasion from an engineered human micro-tumor of MDA-MB-231 breast cancer cells through a type I collagen matrix and escape into a lymphatic-like cavity. By varying the physical properties of the collagen, we have found that MDA-MB-231 tumor cells invade and escape faster in lower-density ECM. These effects are mediated by the ECM pore size, rather than by the elastic modulus or interstitial flow speed. Our results underscore the importance of ECM structure in the vascular escape of human breast cancer cells.

Aeration requirement and energy consumption of reactor-composting of rose pomace influenced by C/N ratio.

As the composting industry develops rapidly in the world, the compost producers have focused on the efficiency of energy utilization in production without restricting the quality of compost in the forced ventilation systems. Therefore, this experimental study quantified the impacts of initial C/N ratio on aeration requirement and energy consumption due to aeration for reactor composting of rose pomace through kinetics of the process using fifteen 100-l composting reactors. The results of the study showed that initial C/N ratio significantly affected decomposition rate, compost maturity, and dry matter losses and organic matter losses (P < 0.05). The maximum decomposition rate (0.072 day-1) and the highest degree of progression of the composting process existed at the mixture with initial C/N ratio of 24.26. The results underlined the importance of the initial C/N of composting of rose pomace in terms of energy consumption due to aeration. In particular, more mature compost within a short time can be obtained when composting was operated with a C/N ratio of 23.7-25.8 in the expense of requiring more airflow rate, fan power, and energy consumption by aeration fan per composting material.

All-electrical monitoring of bacterial antibiotic susceptibility in a microfluidic device.

The lack of rapid antibiotic susceptibility tests adversely affects the treatment of bacterial infections and contributes to increased prevalence of multidrug-resistant bacteria. Here, we describe an all-electrical approach that allows for ultrasensitive measurement of growth signals from only tens of bacteria in a microfluidic device. Our device is essentially a set of microfluidic channels, each with a nanoconstriction at one end and cross-sectional dimensions close to that of a single bacterium. Flowing a liquid bacteria sample (e.g., urine) through the microchannels rapidly traps the bacteria in the device, allowing for subsequent incubation in drugs. We measure the electrical resistance of the microchannels, which increases (or decreases) in proportion to the number of bacteria in the microchannels. The method and device allow for rapid antibiotic susceptibility tests in about 2 h. Further, the short-time fluctuations in the electrical resistance during an antibiotic susceptibility test are correlated with the morphological changes of bacteria caused by the antibiotic. In contrast to other electrical approaches, the underlying geometric blockage effect provides a robust and sensitive signal, which is straightforward to interpret without electrical models. The approach also obviates the need for a high-resolution microscope and other complex equipment, making it potentially usable in resource-limited settings.

Characterization and manipulation of single nanoparticles using a nanopore-based electrokinetic tweezer.

Manipulation and characterization of nanoscale objects through electrokinetic techniques offer numerous advantages compared to the existing optical methods and hold great potential for both fundamental research and practical applications. Here we present a novel electrokinetic tweezer for single nanoparticle manipulation and characterization based on electrokinetic trapping near a low-aspect-ratio nanopore. We find that this nanopore-based electrokinetic tweezer share lots of similarity with optical tweezers and can be modeled as an overdamped harmonic oscillator, with the spring constant of the system being the trap stiffness. We show that different values of ionic currents through the nanopore and trap stiffnesses are achieved when trapping nanoparticles with different sizes (down to 100 nm) and/or zeta potentials. We also demonstrate that the trap stiffness and nanoparticle position can be easily tuned by changing the applied voltage and buffer concentration. We envision that further development of this electrokinetic tweezer will enable various advanced tools for nanophotonics, drug delivery, and biosensing.

Solar Tunnel Drying: Pretreatment on drying kinetic of plum tomatoes / Secagem de Túnel Solar: O efeito do pré-tratamento na secagem cinética de tomates de ameixa

ABSTRACT: Drying of thin layer tomato was studied using a solar tunnel dryer under the ecological conditions of Isparta, Turkey. During drying process, solar irradiation, drying air temperature, relative humidity, and air velocity were measured constantly in different parts of the dryer. Drying runs were performed using plum tomatoes, characterized by an oval shape, intense red color. The change of tomatoes mass was measured daily. The color measurements of dried products were determined at the beginning and end of experiment. In this study, the fresh tomato samples were sorted, graded, washed in water and then sliced into quarters and halves before pretreated. Sun drying behavior of half and quarter sliced tomatoes pretreated with 10% NaCl solution and non-pretreated was investigated. Results showed that the drying time for pretreated and non-pretreated samples was not significantly different. However, drying time and drying rates were affected by number of tomato slices (quarter and half). Drying characteristic curves were evaluated against thirteen mathematical models and the Midilli et al model was the best descriptive model for solar tunnel drying of thin layer tomato. Color analysis emphasized that if tomatoes are pretreated with 10% NaCl solution, they should be sliced in quarter for better quality.

RESUMO: A secagem do tomate de camada fina foi estudada usando um secador de túnel solar sob as condições ecológicas de Isparta, na Turquia. Durante o processo de secagem, a irradiação solar, a temperatura do ar de secagem, a umidade relativa e a velocidade do ar foram medidas constantemente em diferentes partes do secador. As operações de secagem foram realizadas com tomates ameixa, caracterizados por uma forma oval, cor vermelha intensa. A mudança de massa de tomates foi medida diariamente. As medidas de cor dos produtos secos foram determinadas no início e no final da experiência. Neste estudo, as amostras de tomate fresco foram classificadas, lavadas em água e depois cortadas em quartos e metades antes do pré-tratamento. O comportamento de secagem ao sol do tomate em fatias de meio e quarto pré-tratadas com solução de NaCl a 10% e sem pré-tratamento foi investigado. Os resultados mostraram que o tempo de secagem para amostras pré-tratadas e não pré-tratadas não foram significativamente diferentes. No entanto, o tempo de secagem e as taxas de secagem foram afetadas pelo número de fatias de tomate (trimestre e meio). As curvas características de secagem foram avaliadas contra treze modelos matemáticos, sendo que o modelo de Midilli et al foi o melhor modelo descritivo para secagem em túnel solar de tomate de camada fina. A análise de cores enfatizou que se os tomates forem pré-tratados com solução de NaCl a 10%, eles devem ser cortados em fatias para melhor qualidade.

Modeling of road traffic noise and traffic flow measures to reduce noise exposure in Antalya metropolitan municipality.

BACKGROUND: Road traffic noise influencing directly public health in the modern cities is a growing problem in both developing and developed countries. The objective of this study was to model traffic-induced noise in Antalya province, validate the model with noise emission data, and to run the model for the noise preventive scenarios. METHODS: In this study, modeling of traffic-induced noise was performed using SoundPLAN® software at Gazi Boulevard in the city of Antalya. Calculations were made according to NMPB-Routes 96, which have been accepted by environmental noise legislation of the European Union and Turkey. Fundamental data sets such as geographical, topographical and meteorological data, building information and population, traffic network, traffic volume and vehicle speed, and composition of types of vehicle were utilized for the development of noise prediction model. Eight preventive scenarios to reduce traffic-induced noise levels were simulated using the validated model considering traffic flow measures such as types of vehicles, vehicle speeds, types of road surface, redirecting portion of heavy vehicles to alternative routes and noise barrier usage. RESULTS: Results showed that increase in heavy vehicle speeds in smooth road surface conditions caused more increase in exposures than that of light vehicle speed. It was highlighted that it would be appropriate to use porous road surface to reduce exposures on population on high-speed roads. Furthermore, the number of people that are exposed to noise is significantly reduced by precautions such as alternative routes for heavy vehicles and speed restriction. These precautions reduced noise exposures by 25.5-63.8%. The results showed that the usage of noise barrier at the alternative routes in case of porous asphalt road reduced population, dwellings, and area exposed to traffic noise which is greater than 75 dB(A) as 63.8, 40.5, and 60.0%, respectively. CONCLUSION: It could be concluded that the outcomes of the noise prediction models based on the generated scenarios could be used for the purpose of decision support system and could be helpful for decision-makers on the noise legislations.

The effect of FAS and C/N ratios on co-composting of sewage sludge, dairy manure and tomato stalks.

This study was conducted to determine the effects of C/N ratio and free air space in co-composting of sewage sludge with tomato stalk and dairy manure. Experiments were carried out in 100 L of stainless steel aerobic compost reactors with full automation system and monitored for 32 days. The temperature was controlled according to the Rutgers strategy. During the composting process, moisture content, organic matter content, pH, electrical conductivity, total carbon, total nitrogen, C/N ratio, total phosphorus, potassium, NH4+-N, NO3--N and heavy metals contents were determined. For evaluation of the stabilization process, organic matter, dry matter, ammonia and mass and volume losses and temperature index values were taken into consideration. The temperature pattern in the mixtures with dairy manure increased rapidly and reached higher levels depending on dairy manure ratio. The highest organic matter loss was 57.87%, which was in the mixture with a C/N ratio of 20 and a free air space ratio of 37%.

Microfluidic detection of movements of Escherichia coli for rapid antibiotic susceptibility testing.

Various nanomechanical movements of bacteria provide a signature of bacterial viability. Most notably, bacterial movements have been observed to subside rapidly and dramatically when the bacteria are exposed to effective antibiotics. Thus, monitoring bacterial movements, if performed with high fidelity, could offer a path to various clinical microbiological applications, including antibiotic susceptibility tests. Here, we introduce a robust and ultrasensitive electrical transduction technique for detecting the nanomechanical movements of bacteria. The technique is based on measuring the electrical fluctuations in a microfluidic channel, which the bacteria populate. The swimming of planktonic bacteria and the random oscillations of surface-immobilized bacteria both cause small but detectable electrical fluctuations. We show that this technique provides enough sensitivity to detect even the slightest movements of a single cell; we also demonstrate an antibiotic susceptibility test in a biological matrix. Given that it lends itself to smooth integration with other microfluidic methods and devices, the technique can be developed into a functional antibiotic susceptibility test, in particular, for urinary tract infections.

Co-composting of two-phase olive-mill pomace and poultry manure with tomato harvest stalks.

In this study, two-phase olive-mill pomace with poultry manure and chopped tomato harvest stalks were composted at different initial carbon/nitrogen (C/N) ratios with fixed free air space of 35%. Composting experiment was carried out in the 15 aerobic reactors made of stainless steel and was monitored for 28 days. During the composting process, temperature, moisture content, organic matter (OM), pH, electrical conductivity, oxygen and carbon dioxide concentrations, total carbon, total nitrogen, ammonium nitrogen ([Formula: see text]), nitrate nitrogen ([Formula: see text]), and total phosphorus were monitored. Compost mass and volume changes were determined at the beginning, during remixings, and at the end of composting. While the stabilization period took less time for the mixtures containing a high amount of poultry manure, the mixtures having the high portion of two-phase olive-mill pomace took a longer time due to the structure of olive stone and its lignin content. Dry matter loss (range: 18.1-34.0%.) in the mixtures increased with an increase in the share of poultry manure and tomato stalks in the initial mixture. OM loss (range: 21.7-46.1%) for tomato stalks (measured separately) during composting increased due to an increase in the ratio of poultry manure in the initial mixtures.

Dynamics of Interstitial Fluid Pressure in Extracellular Matrix Hydrogels in Microfluidic Devices.

In order to understand how interstitial fluid pressure and flow affect cell behavior, many studies use microfluidic approaches to apply externally controlled pressures to the boundary of a cell-containing gel. It is generally assumed that the resulting interstitial pressure distribution quickly reaches a steady-state, but this assumption has not been rigorously tested. Here, we demonstrate experimentally and computationally that the interstitial fluid pressure within an extracellular matrix gel in a microfluidic device can, in some cases, react with a long time delay to external loading. Remarkably, the source of this delay is the slight (∼100 nm in the cases examined here) distension of the walls of the device under pressure. Finite-element models show that the dynamics of interstitial pressure can be described as an instantaneous jump, followed by axial and transverse diffusion, until the steady pressure distribution is reached. The dynamics follow scaling laws that enable estimation of a gel's poroelastic constants from time-resolved measurements of interstitial fluid pressure.

Co-composting of rose oil processing waste with caged layer manure and straw or sawdust: effects of carbon source and C/N ratio on decomposition.

Rose oil is a specific essential oil that is produced mainly for the cosmetics industry in a few selected locations around the world. Rose oil production is a water distillation process from petals of Rosa damascena Mill. Since the oil content of the rose petals of this variety is between 0.3-0.4% (w/w), almost 4000 to 3000 kg of rose petals are needed to produce 1 kg of rose oil. Rose oil production is a seasonal activity and takes place during the relatively short period where the roses are blooming. As a result, large quantities of solid waste are produced over a limited time interval. This research aims: (i) to determine the possibilities of aerobic co-composting as a waste management option for rose oil processing waste with caged layer manure; (ii) to identify effects of different carbon sources - straw or sawdust on co-composting of rose oil processing waste and caged layer manure, which are both readily available in Isparta, where significant rose oil production also takes place; (iii) to determine the effects of different C/N ratios on co-composting by the means of organic matter decomposition and dry matter loss. Composting experiments were carried out by 12 identical laboratory-scale composting reactors (60 L) simultaneously. The results of the study showed that the best results were obtained with a mixture consisting of 50% rose oil processing waste, 64% caged layer manure and 15% straw wet weight in terms of organic matter loss (66%) and dry matter loss (38%).

Non-invasive mapping of interstitial fluid pressure in microscale tissues.

This study describes a non-invasive method for mapping interstitial fluid pressure within hydrogel-based microscale tissues. The method is based on embedding (or forming) a tissue within a silicone (PDMS) microfluidic device, and measuring the extremely slight displacement (<1 µm) of the PDMS optically when the device is pressurized under static and flow conditions. The displacement field under uniform pressure provides a map of the local device stiffness, which can then be used to obtain the non-uniform pressure field under flow conditions. We have validated this method numerically and applied it towards determining the hydraulic properties of tumor cell aggregates, blind-ended epithelial tubes, and perfused endothelial tubes that were all cultured within micropatterned collagen gels. The method provides an accessible tool for generating high-resolution maps of interstitial fluid pressure for studies in mechanobiology.

Monolithic integration of a nanomechanical resonator to an optical microdisk cavity.

We report a Silicon nano-opto-mechanical device in which a nanomechanical doubly-clamped beam resonator is integrated to an optical microdisk cavity. Small flexural oscillations of the beam cause intensity modulations in the circulating optical field in the nearby microdisk cavity. By monitoring the corresponding fluctuations in the cavity transmission via a fiber-taper, one can detect these oscillations with a displacement sensitivity approaching 10 fm·Hz-1/2 at an input power level of 50 µW. Both the in-plane and out-of-plane fundamental flexural resonances of the beam can be read out by this approach - the latter being detectable due to broken planar symmetry in the system. Access to multiple mechanical modes of the same resonator may be useful in some applications and may enable interesting fundamental studies.